ATSM International has established several standards for evaluating certain characteristics of metallic and non-metallic powders utilized in selective fusion- or sinter-based AM processes. Generally, the established standards for AM powders pertain to various measures of powder flow rates and densities. However, there exist few, if any established standards or standardized tools for evaluating AM powder spreadability; that is, the ease and consistency with which a given AM powder can be physically distributed in a continuous layer of substantially uniform thickness utilizing a spreading motion, such as a motion similar to that of a recoater contained in a powder bed AM machine.
The lack of convenient tools and standardization for assessing the spreadability of AM powders can be problematic in that powder morphology (particle size and shape) can vary significantly between powder suppliers, production lots, and material types. Moreover, the atomization processes commonly employed to produce AM powders may yield powders having substantial variance in morphology within the same production lot. The usage of AM powders having sub-optimal spreadabilities can detract from the reliability and performance of AM machines; and, in certain cases, may degrade the structural integrity of components fabricated from the such powders. Consequently, in instances in which a selected AM powder is loaded into an AM machine, and it is only subsequently discovered that the selected powder possesses a poor spreadability, removal of the powder from the machine may be warranted. Depending upon machine design, AM powder removal can be a cumbersome and time-consuming process, which prolongs machine downtime, suppresses throughput, and increases the overall cost and duration of the AM process.
An ongoing demand thus exists for the provision of devices and methods useful in assessing the spreadability of powders utilized in AM processes. Ideally, such devices and methods would enable rapid visual evaluation of powder spreadability in a reliable and consistent manner to, for example, support the establishment of commonly-accepted standards governing powder spreadability. It would also be desirable if, in at least some embodiments, such devices and methods were capable of emulating the spreading action of a recoater of the type commonly found in powder bed AM machines. Other desirable features and characteristics of embodiments of the present invention will become apparent from the subsequent Detailed Description and the appended Claims, taken in conjunction with the accompanying drawings and the foregoing Background.